1. Technical Field
The present invention relates to a vehicle headlamp and more particularly to a vehicle headlamp that has a light source unit aiming mechanism.
2. Description of the Related Art
One of the specifications employed in a vehicle headlamp is a “visual aiming specification.” According to the visual aiming specification, though the light source unit is accommodated in the lamp body and is tiltably supported by an aiming mechanism, and an aiming screw turning operation portion for tiltably adjusting the light source unit is provided outside the lamp body, the aiming screw turning operation portion is covered by, for instance, a cap so that the adjustment of aiming of the light source can be conducted only by auto manufacturers and such by users (vehicle owners) is inhibited.
In the typical headlamp that complies with the visual aiming specification, as shown in FIGS. 9 to 11, a reflector 202 that has a bulb 206 as its light source is supported by an aiming mechanism that is comprised of a ball joint 205 and two aiming screws 203 and 204 extending longitudinally through a lamp body 201. The aiming screws 203 and 204 are respectively provided so as to be turned at locations where they penetrate the lamp body 201. Bearings of the reflector 202, which are to be supported by the aiming screws 203 and 204, are tightly fitted to a bracket on the reflector 202 side and are constructed as nut members 207 and 208 into which the aiming screws 203 and 204 are screwed, respectively.
In this structure, when the aiming screws 203 and 204 are turned, the nut members 207 and 208 are moved forward or backward along the aiming screws 203 and 204, and the reflector 202 tilts around the horizontal axis Lx and the vertical axis Ly, respectively. The light axis of the lamp is thus tiltably adjusted (aimed) vertically and laterally. Turning operation portions 203a, 204a for making the turning operation of the screws 203 and 204 possible by engagement of an aiming tool such as a screwdriver D or an Allen wrench are respectively formed at the rear end portions of the aiming screws 203 and 204 that extend behind the lamp body 201.
Auto manufacturers make shipment of their vehicles after having the headlamps structured above installed in the vehicles. Before the vehicles are shipped, aiming in the headlamps is carried out by, for example, engaging the screwdriver D with the turning operation portions 203a, 204a. However, vehicle headlamps for, for instance, the United States must meet a specification that does not allow users to perform lateral aiming. Thus, depending upon the destination countries, the visual aiming specification needs to be adopted for the headlamps; and for these destination countries, a construction of a headlamp that meets the visual aiming specification is obtained by, after the aiming has been completed, covering the turning operation portion 203a with a hardly removable cap 210 and thus enveloping the turning operation portion 203a as shown in FIG. 12, as disclosed in Japanese Patent Application Laid-Open (Kokai) No. H11-70832 (paragraphs 0076 to 0089, FIGS. 35 to 40).
However, according to the prior art as described above, since the turning operation portion needs to be covered by the cap 210 after aiming has been carried out, a headlamp manufacturer needs to send a headlamp and a cap as a pair (or separately) to auto manufacturers, which is very troublesome. The auto manufacturer, on the other hand, faces considerable troublesomeness because the cap, which is small in size, must be kept in safe custody so as not to be lost. In addition, the operation of covering the turning operation portion with the cap by workers who need to insert hands into a narrow space behind the lamp body is quite bothersome.